Search for: energy-dispersive-spectroscopy
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Total 114 records

    An investigation on the wetting of polycrystalline alumina by aluminium

    , Article Journal of Materials Processing Technology ; Volume 197, Issue 1-3 , 2008 , Pages 156-160 ; 09240136 (ISSN) Sangghaleh, A ; Halali, M ; Sharif University of Technology
    In this report, sessile drop technique was employed to study the wetting of alumina by pure aluminium. Contact angle of pure aluminium on the surface of polycrystalline alumina substrate was studied in the temperature range of 750-1100 °C. Electron microscopy and EDX analysis were employed to examine the possible reactions at the melt-substrate interface. It was found that at temperatures in excess of 1050 °C molten aluminium can wet alumina. No reaction layer was detected at the Al/Al2O3 interface. © 2007 Elsevier B.V. All rights reserved  

    Dry sliding wear behavior of SiCP/QE22 magnesium alloy matrix composites

    , Article Materials Science and Engineering A ; Volume 435-436 , 2006 , Pages 653-657 ; 09215093 (ISSN) Abachi, P ; Masoudi, A ; Purazrang, K ; Sharif University of Technology
    In present work, an attempt has been made to investigate the wear behavior of particle reinforced composites based on one of the proper magnesium alloys. The SiCP/QE22 composites and QE22 unreinforced specimens were produced via the powder metallurgy route. The volume fractions of SiC particles with three different shapes, i.e. sharp, blocky and round, were selected in the range of 10-25 vol.%. The dry sliding tests were conducted on unreinforced matrix and SiCP/QE22 composites using pin-on-disk apparatus, according to ASTM G99-95a standard. The applied loads were selected as 3, 5 and 20 N. The tests were carried out under sliding speeds of 0.5 and 1.2 m/s. In all tests, the sliding... 

    Growth and characterization of TixNi1-x shape memory thin films using simultaneous sputter deposition from separate elemental targets

    , Article Thin Solid Films ; Volume 491, Issue 1-2 , 2005 , Pages 190-196 ; 00406090 (ISSN) Sanjabi, S ; Sadrnezhaad, S. K ; Yates, K. A ; Barber, Z. H ; Sharif University of Technology
    The fabrication of TixNi1-x shape memory films using simultaneous magnetron sputtering from two separate, elemental targets was investigated. The films were deposited at room temperature and then annealed at 500 °C to achieve the shape memory effect. The influence of sputtering parameters such as power ratio to the targets (to control the composition) and Ar gas pressure (to control the film structure) were studied. It was found that the Ar gas pressure had a critical influence on the shape memory effect of the films. Characterization of the films was carried out by energy dispersive X-ray spectroscopy in a scanning electron microscope (to measure the film composition and uniformity), in... 

    Electropolishing effect on corrosion resistance of electrodeposited nanocrystalline Ni-Mo alloy coatings in NaCl solution

    , Article ECS Transactions ; Volume 45, Issue 19 , 2013 , Pages 65-76 ; 19385862 (ISSN) ; 9781623320355 (ISBN) Roozbehani, B ; Allahyarzadeh, M. H ; Ashrafi, A ; Shadizadeh, S. R ; Seddighian, A ; Sharif University of Technology
    The aim of current research is to investigate the substrate electropolishing effect on corrosion resistance of Ni-Mo thin films. For this purpose, corrosion resistance of coatings deposited on mild steel substrates, that was electropolished or mechanically polished, have been compared in 3.5 wt.% NaCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The structural properties of Ni-Mo thin films were evaluated using X-ray diffraction (XRD) and their morphology, microstructure and chemical composition were also investigated using scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). Temperature and acidity of deposition... 

    Laser welding of NiTi shape memory alloy: Comparison of the similar and dissimilar joints to AISI 304 stainless steel

    , Article Optics and Laser Technology ; Volume 54 , 2013 , Pages 151-158 ; 00303992 (ISSN) Mirshekari, G. R ; Saatchi, A ; Kermanpur, A ; Sadrnezhaad, S. K ; Sharif University of Technology
    The unique properties of NiTi alloy, such as its shape memory effect, super-elasticity and biocompatibility, make it ideal material for various applications such as aerospace, micro-electronics and medical device. In order to meet the requirement of increasing applications, great attention has been given to joining of this material to itself and to other materials during past few years. Laser welding has been known as a suitable joining technique for NiTi shape memory alloy. Hence, in this work, a comparative study on laser welding of NiTi wire to itself and to AISI 304 austenitic stainless steel wire has been made. Microstructures, mechanical properties and fracture morphologies of the... 

    Microstructure and mechanical properties of MoSi2-MoSi2 joints brazed by Ag-Cu-Zr interlayer

    , Article Materials and Design ; Volume 49 , August , 2013 , Pages 197-202 ; 02613069 (ISSN) Hatami Ramsheh, H ; Faghihi Sani, M. A ; Kokabi, A. H ; Sharif University of Technology
    Elsevier Ltd  2013
    The present work investigates joining of two MoSi2 parts through Cusil/Zr/Cusil interlayer with Cusil being a commercial eutectic of Cu-Ag alloy. The joining operation was implemented in an inert gas tube furnace by brazing. The brazing temperature ranged from 800 to 930°C while the operation lasted for 60min. Evaluation of joints strength through shear loading identified the maximum strength 60.31MPa for the brazed sample at 830°C. Interfacial microstructure was studied by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD) techniques. Applying the temperature of 830°C was led to a uniform dense joint consisting of various phases with... 

    Effect of annealing treatment on joint strength of aluminum/steel friction stir lap weld

    , Article Materials and Design ; Volume 44 , 2013 , Pages 487-492 ; 02641275 (ISSN) Movahedi, M ; Kokabi, A. H ; Seyed Reihani, S. M ; Cheng, W. J ; Wang, C. J ; Sharif University of Technology
    In this work, the effects of the annealing temperature and duration on the joint strength of the steel/aluminum lap joints made by friction stir welding were investigated. The strength of the welded joints was evaluated by shear-tensile test. Formation of intermetallic layer at the joint interface and the fracture locations were studied using scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD). The results indicated that longer time of annealing treatment resulted in higher joint strength at 300 and 350 °C and that the rate of the increase in joint strength with time was about 72% higher at the latter temperature... 

    Hydroxyapatite based and anodic titania nanotube biocomposite coatings: fabrication, characterization and electrochemical behavior

    , Article Surface and Coatings Technology ; Volume 287 , 2016 , Pages 67-75 ; 02578972 (ISSN) Ahmadi, S ; Mohammadi, I ; Sadrnezhaad, S. K ; Sharif University of Technology
    Elsevier  2016
    The main challenges of biological implants are suitable strength, adhesion, biocompatibility and corrosion resistance. This paper discusses fabrication, characterization and electrochemical investigation of anodized Ti6Al4V without and with a hydroxyapatite (HA) layer, HA/TiO2 nanoparticles (NPs) and HA/TiO2 nanotubes (HA/anodized). X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS) were used to characterize and compare properties of different samples. Dense HA with uniform distribution and 12.8 ± 2 MPa adhesive strength enhanced to 19.2 ± 4 MPa by the addition of TiO2 nanoparticles and enhanced to 23.1 ± 4 MPa by the... 

    A simple label-free electrochemical DNA biosensor based on carbon nanotube-DNA interaction

    , Article RSC Advances ; Volume 6, Issue 19 , 2016 , Pages 15592-15598 ; 20462069 (ISSN) Shahrokhian, S ; Salimian, R ; Kalhor, H. R ; Sharif University of Technology
    Royal Society of Chemistry  2016
    A simple platform based on a hairpin oligonucleotide switch and multi-walled carbon nanotubes (MWCNTs) for the ultrasensitive detection of specific DNA sequences has been developed. In this approach, the π-stacking interaction of single-strand DNA-MWCNT was employed to construct an electrochemical DNA biosensor. Changes to the surface conductivity, based on the MWCNT replacement, were monitored by using the electrochemical species [Fe(CN)6]3-/4- as a redox probe. Morphological and voltammetric characterizations of the electrode surface were performed using atomic force microscopy (AFM), energy dispersive spectroscopy (EDS), cyclic voltammetry (CV), differential pulse voltammetry (DPV) and... 

    Microstructural and failure analysis of welded primary reformer furnace tube made of HP-Nb micro alloyed heat resistant steel

    , Article Engineering Failure Analysis ; Volume 68 , 2016 , Pages 32-51 ; 13506307 (ISSN) Attarian, M ; Karimi Taheri, A ; Jalilvand, S ; Habibi, A ; Sharif University of Technology
    Elsevier Ltd  2016
    In this paper, the failure of the reformer furnace tube, made of HP-Nb micro alloyed heat resistant steel is investigated. The failure was due to a longitudinal crack developing in the circumferential weld joint close to the outlet end of the tube, where the mean wall temperature had reached the highest value during service. According to the temperature records during the period of 7 years of being in service, the tube had experienced temperatures higher than the tubes designed temperature. This situation besides the occurrence of several sudden shutdowns caused the mechanical properties degradation.Macroscopic and microscopic examinations revealed that the failure had occurred due to the... 

    Synthesis and characterization of supportless Ni-Pd-CNT nanocatalyst for hydrogen production via steam reforming of methane

    , Article International Journal of Hydrogen Energy ; Volume 43, Issue 3 , 2018 , Pages 1319-1336 ; 03603199 (ISSN) Chaichi, A ; Sadrnezhaad, S. K ; Malekjafarian, M ; Sharif University of Technology
    Elsevier Ltd  2018
    Supportless Ni-Pd-0.1CNT foamy nanocatalyst with specific surface area of 611.3 m2/g was produced by electroless deposition of nickel, palladium and multiwall carbon nanotube (MWCNT) on interim polyurethane substrate. Application of temperature programmed reduction (TPR) and temperature programmed oxidation (TPO) data into Kissinger (Redhead) kinetic model showed lessening of their activation energies due to Pd and CNT addition. Presence of foamy Ni/SiC caused 8% higher steam reforming of methane; while Ni-Pd-0.1CNT presence resulted in 22% higher methane conversion. The catalytic behavior of the samples was described by morphological and compositional studies which were carried out by... 

    Polyphosphate-reduced graphene oxide on Ni foam as a binder free electrode for fabrication of high performance supercapacitor

    , Article Electrochimica Acta ; Volume 296 , 2019 , Pages 130-141 ; 00134686 (ISSN) Talebi, M ; Asen, P ; Shahrokhian, S ; Ahadian, M. M ; Sharif University of Technology
    Elsevier Ltd  2019
    Polyphosphate reduced graphene oxide on Ni foam (PPO-RGO/NF) is synthesized by varying weight ratios of Na5P3O10 (PO): graphene oxide (GO) with a simple, scalable and low cost method through freeze-drying of the PO-GO/NF followed by thermal treatment of the prepared electrodes. The resulting samples are characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), Brunauer-Emmett-Teller (BET), and raman spectroscopy methods. The results show that the weight ratio of PO:GO, considerably affect the... 

    Sound velocity in severely deformed aluminum alloys: AA1100 and AA2024

    , Article Applied Physics A: Materials Science and Processing ; Volume 126, Issue 4 , 2020 Yaghoubi, F ; Khani Moghanaki, S ; Kazeminezhad, M ; Sharif University of Technology
    Springer  2020
    The effects of severe plastic deformation on properties of AA1100 and AA2024 including the ultrasound velocity and the shear strength during multi-axial compression (MAC) are studied. Additionally, optical microscopy, scanning electron microscopy, and X-ray energy-dispersive spectroscopy are utilized. For both AA1100 and AA2024, an opposite trend is reported in the shear strength and the sound velocity versus deformation strain of MAC. At high strain range, AA1100 and AA2024 samples reach a plateau in the strength due to the occurrence of dynamic recovery. On the other hand, the sound velocity is shown to decrease 11% and 15% for AA1100 and AA2024, respectively. Furthermore, the... 

    The effect of Ag incorporation on the characteristics of the polymer derived bioactive silicate phosphate glass-ceramic scaffolds

    , Article Boletin de la Sociedad Espanola de Ceramica y Vidrio ; 2021 ; 03663175 (ISSN) Paryab, A ; Godary, T ; Khalilifard, R ; Malek Khachatourian, A ; Abdollahi, F ; Abdollahi, S ; Sharif University of Technology
    Sociedad Espanola de Ceramica y Vidrio  2021
    In the bone tissue engineering field (BTE), it is of significant importance to develop bioactive multifunctional scaffolds with enhanced osteoconductivity, osteoinductivity, and antibacterial properties required for lost bone tissue regeneration. In this work, a bioactive glass-ceramic scaffold was manufactured via a novel polymer-derived ceramics (PDC) manufacturing method. To gain antibacterial properties, the silver ions were incorporated in controlled amount along with other precursors in the PDC processing stage. Microstructural and structural properties of the fabricated silicate-phosphate glass-ceramic scaffold were evaluated by scanning electron microscopy (SEM) equipped with energy... 

    Effect of bonding parameters on microstructure development during TGTLP bonding of Al7075 alloy

    , Article Philosophical Magazine ; Vol. 94, issue. 11 , Mar , 2014 , pp. 1166-1176 ; ISSN: 14786435 Afghahi, S. S. S ; Ekrami, A ; Farahany, S ; Jahangiri, A ; Sharif University of Technology
    The effect of temperature, pressure and bonding time on microstructure of temperature gradient transient liquid phase (TGTLP) diffusion bonded Al7075 alloy using liquid gallium interlayer was investigated. The selected bonding method relies on using the minimum amount of liquid gallium on faying surfaces, using a very fast heating rate to reach the joining temperature and imposing a temperature gradient across the bond region. The microstructure of the diffusion bonded joints was evaluated by light optical microscopy, scanning electron microscopy and energy dispersive spectroscopy (EDS). Results show that by increasing the temperature, pressure and time of joining, a more uniform... 

    Microstructural evolution and fracture behavior of friction-stir-welded Al-Cu laminated composites

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Vol. 45, issue. 1 , 2014 , pp. 361-370 Beygi, R ; Kazeminezhad, M ; Kokabi, A. H ; Sharif University of Technology
    In this study, we attempt to characterize the microstructural evolution during friction stir butt welding of Al-Cu-laminated composites and its effect on the fracture behavior of the joint. Emphasis is on the material flow and particle distribution in the stir zone. For this purpose, optical microscopy and scanning electron microscopy (SEM) images, energy-dispersive spectroscopy EDS and XRD analyses, hardness measurements, and tensile tests are carried out on the joints. It is shown that intermetallic compounds exist in lamellas of banding structure formed in the advancing side of the welds. In samples welded from the Cu side, the banding structure in the advancing side and the hook... 

    Combinatorial screening of nanoclay-reinforced hydrogels: a glimpse of the "holy grail" in orthopedic stem cell therapy?

    , Article ACS Applied Materials and Interfaces ; Volume 10, Issue 41 , 2018 , Pages 34924-34941 ; 19448244 (ISSN) Hasany, M ; Thakur, A ; Taebnia, N ; Kadumudi, F. B ; Shahbazi, M. A ; Pierchala, M. K ; Mohanty, S ; Orive, G ; Andresen, T. L ; Foldager, C. B ; Yaghmaei, S ; Arpanaei, A ; Gaharwar, A. K ; Mehrali, M ; Dolatshahi Pirouz, A ; Sharif University of Technology
    American Chemical Society  2018
    Despite the promise of hydrogel-based stem cell therapies in orthopedics, a significant need still exists for the development of injectable microenvironments capable of utilizing the regenerative potential of donor cells. Indeed, the quest for biomaterials that can direct stem cells into bone without the need of external factors has been the "Holy Grail" in orthopedic stem cell therapy for decades. To address this challenge, we have utilized a combinatorial approach to screen over 63 nanoengineered hydrogels made from alginate, hyaluronic acid, and two-dimensional nanoclays. Out of these combinations, we have identified a biomaterial that can promote osteogenesis in the absence of... 

    Nanoporous gold as a suitable substrate for preparation of a new sensitive electrochemical aptasensor for detection of salmonella typhimurium

    , Article Sensors and Actuators, B: Chemical ; Volume 255 , 2018 , Pages 1536-1544 ; 09254005 (ISSN) Ranjbar, S ; Shahrokhian, S ; Nurmohammadi, F ; Sharif University of Technology
    Elsevier B.V  2018
    Nowadays, achievement to easy, fast, reliable and cost-effective techniques and tools is one of the most important challenges in detection of microorganisms. Salmonella typhimurium is one of the most important pathogenic bacteria that affect the human health and environmental infections. In this work we report a new, stable, biocompatible and cost-effective platform for construction of an aptasensor based on nanoporous gold (NPG) for detection of S. typhimurium. Nanoporous gold is electrochemically synthesized using Au-Cu alloy at the surface of Au/GCE. Thiol functionalized aptamer is used for effective linking to the surface of NPG/Au/GCE via self-assemble monolayers (SAMs) formation.... 

    Structural changes during synthesizing of nanostructured W-20 wt% Cu composite powder by mechanical alloying

    , Article Materials Science and Engineering A ; Volume 445-446 , 2007 , Pages 86-93 ; 09215093 (ISSN) Maneshian, M. H ; Simchi, A ; Razavi Hesabi, Z ; Sharif University of Technology
    Nanostructured W-20 wt% Cu composite powder was synthesized by mechanical alloying (MA) in an Attritor ball mill. The morphological changes and structural evolution of the composite powder during MA was studied by employing scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX), laser particle size analyzer (LPS), inductively coupled plasma (ICP) spectrometry, atomic absorption spectrophotometery (AAS), and the bulk powder density measurement. The results were compared with those obtained from attrition milling of monolithic W and Cu powders processed at the same condition. Whereas the milling mechanism of the monolithic powders follow the ductile (for Cu)... 

    Highly textured ZnO thin films: An economical fabrication, doping by Mn2+ and Sn2+ and approachment for optical devices

    , Article Materials and Design ; Volume 28, Issue 3 , 2007 , Pages 1065-1070 ; 02613069 (ISSN) Vaezi, M. R ; Sadrnezhaad, S. K ; Sharif University of Technology
    Elsevier Ltd  2007
    Fabrication of high quality zinc oxide thin films and analysis on its physical, chemical properties have applications in opto-electronic devices, UV laser, microelectronics and micro-machining schemes. Highly textured ZnO thin film with a preferred (0 0 2) orientation was prepared by two-stage chemical deposition (TSCD) using an aqueous solution containing zinc complex on a soda-lime glass substrate. From the results obtained, it can be shown that the preferred orientations of the film microcrystal changes with the doping process. The film was characterized by X-ray diffraction (XRD), SEM, EDAX, optical technique, Fourier transform infrared spectroscopy (FTIR) in order to qualify its...